This command is used to do low level copying of data.

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25 views

Installing CentOS on HP Server, SSDs connected to a RAID controller

I am trying to install centOS 6.0 in this HP Server, I contacted with the support and they said me that it supports that OS. I have no problem installing it on a SSD that is connected directly to ...
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1answer
24 views

dd: zero-out all the remaining unused space of a drive

In the second answer of this question about disk cloning with 'dd', I read this command: dd if=/dev/zero of=/mnt/hdb/zero It is supposed to write '0' in the unused space of drive 'hdb', however I ...
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1answer
31 views

Using DD to produce an Image results in empty image [closed]

I am trying to take an image of my Android phone. Specifically I have tried to image the system and boot partitions. The imaging process appears to work correctly when using dd. However, when I ...
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5answers
4k views

Break up a dd image into multiple files

I'm doing some data recovery from a hard disk. The disk has about 300GB of data on it, but I lack another hard drive that has 300GB of free space. I have three HDs, with 150, 40, and 120 GB free. ...
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0answers
24 views

Shrinking an img file that contains linux partitions

I've got an img file (4,02GB) containing a Linux OS. My goal is to shrink this img filed down to < 4GB. The img contains a linux partition that only holds about 2,5GB of data. I need to be able to ...
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4answers
26k views

dd on entire disk, but do not want empty portion

I have a disk, say /dev/sda. Here is fdisk -l: Disk /dev/sda: 64.0 GB, 64023257088 bytes 255 heads, 63 sectors/track, 7783 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size ...
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1answer
38 views

Segmentation fault on dd command

I ran this command on Ubuntu to resize the /tmp and after that there is segmentation fault coming. dd if=/dev/zero of=/dev/xvda1 bs=1024M count=2 Its our live server. Is there any way to get it ...
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2answers
5k views

create image of a USB drive without unallocated partition

I have 8GB USB drive attached to my system which looks like this: [root@host]# fdisk -l /dev/sdb Disk /dev/sdb: 8462 MB, 8462008320 bytes 255 heads, 63 sectors/track, 1028 cylinders Units = ...
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3answers
2k views

Cloning LVM partitions

I need to clone a CentOS installation from a 1TB disk partitioned with LVM, to several identical machines. The disk is mostly empty since only the operating system and some software are installed and ...
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2answers
129 views

Acceptable I/O speeds for 6 x 250GB SSDs in RAID 10

I'm running CentOS 7 (XFS filesystem) on a dell server with a PERC H700 raid controller. Inside this server I have 6 x Samsung 850 Evo 250GB SSDs (yes they are consumer drives however, this is a home ...
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1answer
28 views

Backup old disk to external disk (new)

One of the 2 x 500GB drives on server is crashed can read but not write the data, which both are on Hardware RAID 0. So I connected an external 1TB new drive to backup the data and replace those 2 x ...
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2answers
114 views

Cloning a two partition HDD onto a smaller HDD and maintaining MBR

I have a hard disk(A) containing two partitions - A1 is a NTFS partition containing a windows OS, and A2 is an NTFS partition containing data. I want to copy both of these partitions onto a different, ...
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2answers
347 views

How to execute bash script through pxe boot [closed]

Can any one tell me how to execute bash scripts via pxe boot. What I am trying to do is when Raw Server boots up I want to deploy cloned image over hard disk via PXE boot. I am aware that there are ...
7
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1answer
170 views

File is too big for /dev/null

While testing a problem LUN for read errors, I encountered the following problem: find /mnt/problem_lun/ -type f -print -exec dd if={} of=/dev/null bs=8k \; ... /mnt/problem_lun/a_file dd: writing ...
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3answers
114 views

Truncate empy space from a raw dd image

I have a raw disk image I took using dd of a Ubuntu instance. The total disk size is 300 GB, but only 5.5 GB used. Is there a way to resize the raw dd image down to 20 GB, keeping all of the 5.5 GB ...
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1answer
114 views

Create random file with openssl [closed]

So I read this questionUrandom Alternative, but I am unable to make a comment there (without 50 rep) - therefore I open a separate question: If I use this command instead of dd and urandom, how do I ...
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3answers
5k views

/dev/zero equivalent in windows?

I am trying to use the windows version of dd to copy a RHEL iso to a USB stick. However, I wanted to zero out the drive first to ensure there is no filesystem on it before writing it out. Is there an ...
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2answers
90 views

Reduce xen image disk usage

Two cases: 1.If making hdd image using dd and copy it trough nfs to another server: mount -o ro,remount / dd if=/dev/sda bs=64K | gzip -c > /share/test.img.gz then after gunzip I get 20Gb (for ...
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4answers
2k views

Wipe is very slow. Too little entropy?

I have to hand off a Laptop including its hard disc. Since it was not encrypted I wanted to wipe it at least quickly. I know this is not optimal on SSD, but I thought better than just plain readable. ...
1
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1answer
68 views

dd vs. dd pipelined: which is better? [closed]

Here I read, in the comments, that a guy got more performance when used dd in pipeline for a copy. Like for example: dd if=in | dd of=out instead of dd if=in of=out Is it really faster? Why? ...
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2answers
2k views

In Linux, how can I create thin-provisioned file so it can be mounted and a filesystem created on it?

I am building a system that gives users certain amounts of disk space. The way I am doing it is: create a file with dd create an ext4 filesystem inside the file mount the file and tell the user ...
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1answer
55 views

Make a dd image restorable to a smaller drive

Suppose I have a 32 GB USB flash drive (UFD) and an 8 GB UFD. I have a 5 GB partition at the start of the bigger UFD, and the rest is unallocated. The problem is to copy the partition and boot sector ...
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1answer
154 views

Copy LVM volume group spanning two physical volumes on two disks

[update] i have copied the two primary partitions using gparted. now i am stuck trying to copy a single volume because it is made of two physical volumes each on separate disk...ideas? /sda5, /sdb1 = ...
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1answer
49 views

The best way to copy OS on RAID10 and lvm partition

I need to backup/clone the entire operating system. The problem is it's 2TB of data on lvm partition and RAID10 (i do not know is it dedicated controller or fake RAID in BIOS. Probably the second ...
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0answers
308 views

Creating IPsec tunnel Ubuntu 15.04 ip sec tools

I'm trying to setup a VPN/Tunnel between three(3) Ubuntu 15.04 servers. I've googled and it seems that I can use IPsec tools for this. I've only found the following ...
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1answer
70 views

Deleted MBR on virtual machine on purpose, but entries are preserved

I'm playing with Master boot record. I decided to delete and restore it on my vmware machine. With Ubuntu LiveCD I'm trying to erase partition entries and signature with command: dd if=/dev/zero ...
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0answers
379 views

Slow IO Performance with PERC H700/710 with current linux distributions

we noticed really bad write performance, on our new Dell R720 with Perc 710. Especially when it come to writing a lot of small files. The funny thing is that this bad performance only occurs on newer ...
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1answer
482 views

On a system with 64GB mem the Linux Buffer run full while copying with dd to dev null and io stops till manual drop_caches

I am running a server with linux software raid 10. It is a dual CPU system with 64GB Ram. 2x16GB dimms related to each of the CPUs. I want to use dd to backup kvm virtual machines and run into a ...
6
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3answers
303 views

Best way to clone a Linux system

I've just finished setting up a Debian system running on an embedded device. It has custom partitioning, numerous config file changes, web content, and a couple of applications compiled from source. ...
0
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1answer
81 views

ddrescue — which files are in error locations?

I had a HDD crash and had to use ddrescue to restore it. It took a month, but it finally finished today. However, there were three errors that it could not read. Is there a way to find out which files ...
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1answer
192 views

Remote bash script execution via ssh causes local script to stop

I have a setup which behaves in a way i cannot get my head around. So I have a local bash script generateTrafficOnHosts.sh which reads IP addresses from a file. It then calls a bash script ...
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0answers
927 views

Create a VHD file from a Linux disk

I have a disk containing CentOS 5.8 that was removed from a dead box. I would like to make a VHD file from this disk so I can run a virtual machine (instead of a new physical machine). The Virtual ...
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5answers
809 views

Does filling up disk with dd removes files securely?

I want to remove my files securely without worrying about anyone restoring them, I know I can use shred but it takes too long even with -n 1 so I thought maybe if I remove files and write on the disk ...
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3answers
13k views

Moving a Logical Volume directly from one server to another over the network?

I have a KVM host machine with several VMs on it. Each VM uses a Logical Volume on the host. I need to copy the LVs to another host machine. Normally, I would use something like: dd ...
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1answer
271 views

fio on virtual disk created with dd to stress disk

I am trying to create a script for my coworkers to use in the field that will stress the internal disks to a Linux server. I plan to put some logic in for finding the /dev/sd's available and such. But ...
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2answers
495 views

How to mount dd image of digital ocean?

I have created a dd image of /dev/vda using the following command: ssh root@1.2.3.4 "dd if=/dev/vda" | dd of=/home/backup/vda.img and I can't mount it on my local Ubuntu server where I ...
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2answers
633 views

Linux dd: Is there a way to redirect its output for monitoring?

Sometime the servers in my workplace experience some weird behavior, it happens in random physical racks around different DC's around the world. It seems like there's a networking bandwidth issues ...
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1answer
276 views

How can I resume a dd operation after a “error writing in file” status?

This command produced the error mentioned above after 9 h (preparing a 2 TB hdd for encryption): time openssl enc -aes-256-ctr -pass pass:"$(dd if=/dev/urandom \ bs=128 count=1 2>/dev/null | ...
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4answers
3k views

Best way to copy large amount of data between partitions

I'm looking to transfer data across 2 lv of an HP-UX server. I have a couple of those transfers to do, some of which are mostly binary (Oracle tablespace...) and some others are more text files ...
19
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2answers
7k views

Does the “bs” option in “dd” really improve the speed?

Every now and then, I'm told that to increase the speed of a "dd" I should carefully choose a proper "block size". Even here, on ServerFault, someone else wrote that "...the optimum block size is ...
4
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2answers
7k views

Is it possible to restore disk image to a different size hard disk

recently I made a backup 120 GB disk image using dd: dd if=/dev/sda of=backup.img Now I have a new 320 GB hard disk and want to restore that backup image to that new disk. Will running dd ...
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1answer
110 views

Simple scheme for backup virtual machine, which drawback of simple DD?

We've been struggling to create the consistent scheme for backup of KVM virtual machines under Proxmox control and Ceph as storage, but still quite often during the vzdump with a snapshot the virtual ...
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2answers
1k views

Raw copy with sector precision on windows

Is there some program for windows that is able to do what dd does in linux out of the box? I need to copy from a file to a physical disk in raw mode where I need to define offsets for input and ...
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2answers
735 views

How to clone a RAID5 system

I clone single disk systems by booting the master system to a CD and running… dd if=/dev/sda | gzip - | ssh user@hostname dd of=image.gz Then I boot the target system with the CD and run… ssh ...
147
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26answers
291k views

Using DD for disk cloning

There's been a number of questions regarding disk cloning tools and dd has been suggested at least once. I've already considered using dd myself, mainly because ease of use, and that it's readily ...
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9answers
16k views

How to set up disk cloning with dd, netcat and ssh tunnel?

I would like to copy stuff in bulk (reimage disk using dd) with netcat from host A to B via ssh encrypted channel on Linux. What commands should I type on both ends?
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1answer
35 views

Disk image growing in size [closed]

I am trying to set up Rasberry pi for jobs that don't deserve bigger machine. I downloaded a Pidora disk image (.img) zipped it is roughly 512MB. After unzipping it is 2.2GB ( no problem here). ...
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2answers
91 views

HHD cloning with dd on running server

Is it possible to clone HDD with dd command on linux while server is up and running. Server running, Apache, MySql, NGINX. I ask this coz won't have downtime.
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1answer
121 views

When copying VM filesystem over netcat, dd copies double the disk size

I'm attempting to copy the disk of a working headless virtualbox VM (VM1) on one server to a new VM (VM2) on a vCloud server. I don't have access to the host of VM2. The OS is Windows Server 2003 ...
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0answers
1k views

Cloning a bitlocker encrypted disk

Our company's had its laptops for just over 2 years now and they have all become slow and many of them have had their harddisks dying randomly lately. I noticed that many of my colleagues use a tilted ...